PMB 2520 Hammerhead

The PMB 2520 Hammerhead is a one-chip solution for GPS that is produced by Infineon Technologies in cooperation with Global Locate. It allows the usage of assistance data by supporting A-GPS standards.

Modules of the Hammerhead

RF front-end with on-chip, high gain and low noise, LNA, I/Q mixers, on-chip polyphase complex IF filter, digitally controlled AGC, and 3-bits ADC for the I and Q paths.

Sigma-Delta RF PLL with on-chip PCO and on-chip loop filter.

Embedded PLL and NCO for baseband clock generation.

Multiple channels digital mixers and parallel correlator engines to enable real time correlation of the PRN code for up to 14 satellites.

Post processor including peak detection logic

SRAM for storing correlation results

Host Interface

The Hammerhead integrates 3 serial interfaces:

UART

I2C

SPI

The UART in the Hammerhead is a full-duplex UART interface. It is fixed in 8N1(8 data bits, no parity, 1 stop bit) mode. On the GTA01, the host processor connect with the Hammerhead through the UART.

Host software Architecture

The Hammerhead driver software is delivered as a plugin for gpsd.
It provides both high level positioning information in a number of formats, and an interface to feed in the AGPS data.

The gpsd libraries provide the following infomation to the high level software:

Position data

Library status

Time-out and Packet Available

The high level software sends the following messages to the plugin:

Assistance data

Positioning Commands

Configuration Commands

Gpsd communicates with the system at the following part:

Communications Drivers

System Timer

NV storage

Log buffer

GPS on GTA01

At the GTA01, the host processor is a S3C2410.

Hammerhead on the GTA01

On the GTA01, the Hammerhead are configured that connected with the host processor through the UART. The UART of data output/input is connected to the UART 1 of the SC2410. The UART of the hardware flow control is connected to the UART 2 of the SC2410.

Q & A

Q: Can gpsd support Differential GPS.

While the neo does not have any means of receiving DGPS signals directly, it can of course download them from the internet (bluetooth, gprs), either from a server, or peer-peer from stationary (charging?) neos that have GPS signal and cheap internet connections.

This can generate positions accurate to well under a metre, compared to (probably) 2-3m without.

The gpsd plugin is the place that these corrections would need to be done, as they need to be performed on a per-satellite basis, before generating the position.

This is separate from AGPS - AGPS gives information on current satellite position. DGPS is a local minute by minute 'ionospheric weather' for your region.

Q: Can someone upload somewhere an strace of the interaction between gpsd, and the hammerhead chip?

Ideally this would be requesting a GPS position every second, starting from 'cold', with no AGPS data, for at least half an hour, in an area where the reciever can see the sky.

Q: Can I get NMEA data from the GPS?

A: Not directly. However, the gpsd program 'gpspipe', with the -r switch will output NMEA data with the current position information. The right way to do it is to use libgpsd in your program if possible.

PMB 2520 Hammerhead

The PMB 2520 Hammerhead is a one-chip solution for GPS that is produced by Infineon Technologies in cooperation with Global Locate. It allows the usage of assistance data by supporting A-GPS standards.

Modules of the Hammerhead

RF front-end with on-chip, high gain and low noise, LNA, I/Q mixers, on-chip polyphase complex IF filter, digitally controlled AGC, and 3-bits ADC for the I and Q paths.

Sigma-Delta RF PLL with on-chip PCO and on-chip loop filter.

Embedded PLL and NCO for baseband clock generation.

Multiple channels digital mixers and parallel correlator engines to enable real time correlation of the PRN code for up to 14 satellites.

Post processor including peak detection logic

SRAM for storing correlation results

Host Interface

The Hammerhead integrates 3 serial interfaces:

UART

I2C

SPI

The UART in the Hammerhead is a full-duplex UART interface. It is fixed in 8N1(8 data bits, no parity, 1 stop bit) mode. On the GTA01, the host processor connect with the Hammerhead through the UART.

Host software Architecture

The Hammerhead driver software is delivered as a plugin for gpsd.
It provides both high level positioning information in a number of formats, and an interface to feed in the AGPS data.

The gpsd libraries provide the following infomation to the high level software:

Position data

Library status

Time-out and Packet Available

The high level software sends the following messages to the plugin:

Assistance data

Positioning Commands

Configuration Commands

Gpsd communicates with the system at the following part:

Communications Drivers

System Timer

NV storage

Log buffer

GPS on GTA01

At the GTA01, the host processor is a S3C2410.

Hammerhead on the GTA01

On the GTA01, the Hammerhead are configured that connected with the host processor through the UART. The UART of data output/input is connected to the UART 1 of the SC2410. The UART of the hardware flow control is connected to the UART 2 of the SC2410.

Q & A

Q: Can gpsd support Differential GPS.

While the neo does not have any means of receiving DGPS signals directly, it can of course download them from the internet (bluetooth, gprs), either from a server, or peer-peer from stationary (charging?) neos that have GPS signal and cheap internet connections.

This can generate positions accurate to well under a metre, compared to (probably) 2-3m without.

The gpsd plugin is the place that these corrections would need to be done, as they need to be performed on a per-satellite basis, before generating the position.

This is separate from AGPS - AGPS gives information on current satellite position. DGPS is a local minute by minute 'ionospheric weather' for your region.

Q: Can someone upload somewhere an strace of the interaction between gpsd, and the hammerhead chip?

Ideally this would be requesting a GPS position every second, starting from 'cold', with no AGPS data, for at least half an hour, in an area where the reciever can see the sky.

Q: Can I get NMEA data from the GPS?

A: Not directly. However, the gpsd program 'gpspipe', with the -r switch will output NMEA data with the current position information. The right way to do it is to use libgpsd in your program if possible.